<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script>
        var box =document.getElementsByClassName("input");
        for (var i = 0; i < box.length; i++) {
            box[i].onclick = function() {
                for (var j = 0; j < box.length; j++) {
                    box[j].style.background = "";
                    box[j].value = "未点";
                    box[j].style.fontSize = "";
                }
    
                this.style.background = "red";
                this.style.fontSize = "100px"
                this.value = "已点";
    
            }
        }
    </script>
</head>
<body>
    <input type="button" value="未点">
    <input type="button" value="未点">
    <input type="button" value="未点">
    <input type="button" value="未点">
    <input type="button" value="未点">
    <input type="button" value="未点">
    <input type="button" value="未点">
</body>

</html>